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About Visual Testing (VT)

Visual testing is the most commonly used test method in industry. Because most test methods require that the operator look at the surface of the part being inspected, visual inspection is inherent in most of the other test methods. As the name implies, VT involves the visual observation of the surface of a test object to evaluate the presence of surface discontinuities. VT inspections may be by Direct Viewing, using line-of sight vision, or may be enhanced with the use of optical instruments such as magnifying glasses, mirrors, boroscopes, charge-coupled devices (CCDs) and computer-assisted viewing systems (Remote Viewing). Corrosion, misalignment of parts, physical damage and cracks are just some of the discontinuities that may be detected by visual examinations.

Topical Outline

This examination is 2 hours in length, having 90 questions of equal value.

Fundamentals

Vision and light

Ambient conditions

Test object characteristics

Equipment Accessories

Magnifiers/microscopes

Mirrors

Dimensional

Borescopes

Video systems

Machine vision

Replication

Temperature indicating devices and materials

Chemical aids

Surface comparators

Lasers

Applications and Requirements

Raw materials

Primary process materials

Joining processes

Fabricated components

In-service materials

Coatings

Other applications

Requirements

Variables Affecting Results of interpretation/ Evaluations

Equipment including type and intensity of light

Material including the variations of surface finish

Discontinuity

Determination of dimensions (ie: depth, width, length, etc.)

Sampling/scanning

Process for reporting visual discontinuities

Personnel (human factors)

Documentation

Safety

References

The number in parentheses following each reference is the ASNT catalog number.